This invention relates to devices that measure the injector height in internal combustion engines generally and diesel engines specifically.
An internal combustion engine has a plurality of cylinders. Three rocker arms are provided for each cylinder, one of which operates the fuel injector that delivers fuel into the cylinder and the other two of which operate the exhaust valves that exhaust gas from the cylinder. Each set of three rocker arms pivots on a shaft. The rocker arm that operates the fuel injector has one end connected by means of a push rod and a cam follower to the cam shaft. As the cam shaft rotates, the rocker arm is caused to pivot about its shaft. The other end of the rocker arm engages the follower of the associated fuel injector. The fuel injector meters and injects the amount of fuel required to handle the load, atomizes the fuel for mixing with the air in the combustion chamber and performs other related functions. The follower of the fuel injector is spring biased to its closed position and the rocker arm causes the follower to move against such bias.
To time an injector so that the fuel injection occurs at the desired position of the piston within the associated cylinder, the injector follower must be adjusted to a predetermined height in relation to the injector body. This is accomplished in a diesel engine by utilizing a device that measures such height, then loosening a locking nut associated with the push rod and then adjusting the push rod so that the injector follower is at precisely the correct height.
It is common to utilize a pin gauge consisting of a rod passing through a block. The distance between one surface of the block and one end of the rod is known and the injector height is adjusted until it matches such distance. This has not proved to be sufficiently accurate and requires a different gauge with the desired rod length for each engine.
There have been developed gauges incorporating a micrometer dial on which the height can be read to thousandths of an inch. These are more accurate than the pin gauges. One such device currently in the marketplace is sold by Kent-Moore of Roseville, Mich. The tool sold by Kent-Moore is positioned on the injector follower and a plunger thereof engages the injector body. A needle is deflected to a position on the associated dial indicating the height. The Kent-Moore tool is held in place with two legs having cross pins that hook into the coil spring. Each of these legs is spring loaded to hold the tool in place. However, the tool is subject to become dislodged and displaced and even to fall off of the injector follower.